This paper describes an alignment algorithm that estimates the initial heading angle of AUVs (Autonomous Underwater Vehicle) for starting navigation in a sea area. In the basic dead reckoning system, the initial orientation of the vehicle is very important. In particular, the initial heading value is an essential factor in determining the performance of the entire navigation system. However, the heading angle of AUVs cannot be measured accurately because the DCS (Digital Compass) corrupted by surrounding magnetic field in pointing true north direction of the absolute global coordinate system (not the same to magnetic north direction). Therefore, we constructed an experimental constraint and designed an algorithm based on extended Kalman filter using only inertial navigation sensors and a GPS (Global Positioning System) receiver basically. The value of sensor covariance was selected by comparing the navigation results with the reference data. The proposed filter estimates the initial heading angle of AUVs for navigation in a sea area and reflects sampling characteristics of each sensor. Finally, we verify the performance of the filter through experiments.

Abstract
1. 서 론
2. 항법 초기 방위각 정렬 알고리즘
    2.1 시스템 및 환경
    2.2 항법 초기 방위각 측정
    2.3 확장 칼만 필터를 적용한 방위각 추정 알고리즘
3. 항법 알고리즘
4. 실해역 실험
    4.1 실험 환경
    4.2 실험 방식
    4.3 실험 결과
5. 결 론
References

• 김규현(Mechatronics Engineering, Chungnam National University) | Gyu-Hyeon Kim
• 이지홍(Mechatronics Engineering, Chungnam National University) | Jihong Lee Corresponding author
• 이필엽(Hanwha Systems) | Phil-Yeob Lee
• 김호성(Hanwha Systems) | Ho Sung Kim
• 이한솔(Hanwha Systems) | Hansol Lee